Scientific testing, measuring, and diagnostic instruments are used in many industrial applications. Typically, these instruments are used to verify the accuracy of production equipment or verify the assembly of produced goods. The instruments used for this verification must also be periodically tested to ensure that they are operating correctly and yielding valid and accurate measurements. Typically, these instruments are sent to equipment calibration laboratories where measurements obtained from instruments are compared to those obtained from standards to see if the instruments are measuring within predefined specifications. The calibration laboratory may be an independent laboratory operated by a third party or it may be a laboratory operated by the user of the instruments. If an instrument is not within the predefined specifications, the testing technician attempts to adjust the instrument to bring it in compliance with the predefined specifications. Instruments sent to a calibration laboratory for testing are called test instruments in this document and those instruments used to test other instruments are called calibration standards.
The calibration standards used at calibration laboratories must also be verified against other calibration standards until the verification chain ends at a calibration standard of industry recognized authority such as those available from the National Institute of Standards and Technology ("NIST"). The calibration standards maintained at NIST are sometimes referred to as the "golden mean." While "golden mean" and NIST standard are used throughout this document to describe industry recognized standards for verifying equipment accuracy, the reader should appreciate that these terms include any industry recognized standard in any country which is used for such verification. Thus, if a company wants to verify the accuracy of the test instruments that it uses to produce goods or that it uses to verify the quality of its goods, it needs to be able to trace verification of its test instruments back to a "golden mean." Usually, this is accomplished by the records maintained at the calibration laboratory where the company's test instruments are serviced.
In previously known systems used to track data at calibration laboratories, the systems track all of the information on a work order basis. That is, as each test instrument is received at a calibration laboratory, a work order record is generated and assigned a work order number. Included in the work order record are data which identify the company or entity which sent the equipment to the calibration laboratory for calibration, the address and other relevant information regarding the company, equipment data such as the manufacturer and serial number, and other data which may be used to identify the equipment at the time it is received. For example, this other data may include asset numbers assigned by the customer to internally track the equipment at the customer's facility.
After this initial data are collected and stored in a work order record, the equipment is sent to a technician who performs a calibration procedure for testing the accuracy of the equipment. Calibration standards are equipment used by a technician at the calibration laboratory to test and verify the accuracy of test instruments sent to the laboratory for calibration. Calibration standards are verified against NIST standards or the like so test instruments can eventually be traced to a NIST standard, as discussed more fully below. The measurement data obtained from a test instrument and the calibration standards used to perform the measurements are stored in the work order record. If the test instrument is out of calibration, the technician performs an adjustment to bring the test instrument within the predefined specifications for the test instrument. The measurement data obtained once the unit has been adjusted to be within the predefined specifications are also recorded in the work order record. These known data management systems then print a calibration certificate using the data stored in the work order record. The equipment and calibration certificate are then sent to shipping so the equipment may be returned to the customer. Typically, shipping uses the work order number on the calibration certificate to obtain the work order record which identifies the customer and the address to which the equipment is to be sent. Finally, accounting uses the work order record to generate invoices for the services identified in the work order record and these invoices are sent to the customer at the address identified in the work order record.
These previously known laboratory management systems group all the different types of data associated with one calibration service for one test instrument in one record. When a test instrument is returned to the calibration laboratory for subsequent calibration, information is needed to locate the prior work order record because tracking the history of the calibration jobs is important to show the equipment has been properly maintained. In previously known systems, this may not be possible for a number of reasons. For one, data is usually manually entered at each stage of the calibration process in previously known systems. Thus, spelling errors and other typographical errors may be introduced into the records. These errors may subsequently prevent identification of a prior work order record when the equipment is returned to the calibration laboratory.
Another problem with known laboratory data management systems is that information used to identify the equipment may change. For example, the equipment being used by a customer may be associated with a contract which the customer is performing for another entity. If that contract terminates or the equipment is transferred to another contract also being performed by the customer, the asset number used to identify the equipment may change. If the asset number is being used to locate work order records previously performed on a test instrument, those records may not be located because the data field used to locate the data records has changed. As a result, the calibration history for the test instrument may be broken. This broken history is a result of being able to have multiple identifications of a single test instrument in the system as a result of data entry errors or typical changes in equipment identification.
What is needed is a laboratory management system which reduces the likelihood that equipment will be identified more than once so that job history integrity is maintained.
During performance of the calibration procedure, data related to the response of the test instrument is stored along with data about the calibration standard and the test instrument. The data collected usually includes the calibration and expiration dates for the calibration standards used during the calibration procedure, the date of the calibration procedure, and the date the test instrument next needs calibration. This type of information is also recorded each time a calibration standard is calibrated. Thus, one can use this information to identify the standards used to calibrate a test instrument and the corresponding information for the identified calibration standards to eventually trace the calibration of a test instrument to an industry recognized standard. The process of generating a report which contains the information to trace a test instrument measurement to an industry recognized standard is called measurement traceability.
In most calibration laboratories, there are two types of calibration standards--primary standards and transfer standards. Primary standards are calibration standards which are typically verified against industry accepted standards such as NIST standards. Transfer standards are calibration standards which have been verified against primary standards. In previously known calibration laboratory data management systems, each work order for calibration of a test instrument sent by a customer, the calibration standards used, the measurements obtained in the calibration procedure, and the date each standard was last calibrated are recorded on the calibration certificate and stored in the work order record.
To trace a calibration measurement of a test instrument to an industry recognized standard, the calibration certificate may be located in a manual search or from a work order record maintained in an automated system. The standards used for the calibration and the corresponding calibration date for each standard is obtained from the certificate or work order record. In previously known systems, a separate calibration standard file is maintained which includes a date for each calibration of each standard, the standards used at each calibration date to calibrate the standard, and the corresponding calibration date for each laboratory or NIST standard used to calibrate the standard. Thus, in a manual classification system, the calibration certificate for the test instrument is first located, then the calibration certificates for each of the standards used to calibrate the test instrument are then retrieved according to calibration date and the process continues for each of those standards until a certificate is located for each standard which indicates the standard was calibrated against an industry recognized standard such as a NIST standard. A manual search to collect calibration certificates is very labor intensive and expensive.
In previously known automated calibration laboratory data management systems, the work order records must first be searched to locate the latest work order for a test instrument. That record identifies the standards and their calibration dates which were used to calibrate the test instrument. Then the calibration date information is used to search the calibration standard file to locate a record for each standard, and in turn, continue looking for records within the calibration standard file by calibration date which correspond to the laboratory or NIST standards used to calibrate standards. This process continues until a laboratory standard in the chain indicates it was verified against a NIST standard.
There are a number of problems with using previously known automated calibration laboratory data management systems to trace calibration standards to a NIST standard. For one, there is the separate maintenance of both a work order database and a calibration standards database. To effectively trace the calibration of a test instrument, a user, either manually or through an automated interface, must use calibration date information from the work order database to search the calibration standards database. The location of work order records is again subject to the typographical errors and equipment identification changes discussed above. Additionally, the identification of a standard in the work order record may differ from the identification of the calibration standard in the calibration standard database because of typographical errors and other data entry errors.
Another problem which occurs in the tracing of the standards arises from the use of the calibration date to locate information about a calibration standard. Situations may arise where one calibration standard may be used to calibrate a second calibration standard and then the second calibration standard is used to calibrate the first calibration standard on the same day. For example, a calibration standard oscillator may be used to calibrate the frequency sensitivity of a calibration standard frequency counter. Once the frequency counter is calibrated, the oscillator is recorded as the standard used to calibrate the standard frequency counter. The counter may then be used to calibrate the oscillator frequency output and the counter is correspondingly recorded as a standard used to calibrate the standard oscillator. Because known automated tracing systems search for the standard identifier of a standard used to calibrate a test instrument and its most recent calibration date, the system fails to locate the correct calibration standard record or gets caught in a loop. For instance, in the example presented above, use of the frequency counter to calibrate a test instrument results in a trace which first locates the most recent calibration record for the frequency counter. Because the oscillator was used to calibrate the frequency counter, the calibration record for the oscillator is located. Processing the calibration record for the oscillator causes the system to return to the frequency counter calibration record because it was used to calibrate the oscillator on the same day. This loop continues as the system would continuously search for the calibration record for the standard frequency counter used to calibrate the standard oscillator and then return to the standard counter record, which returns to the standard oscillator record, and so on indefinitely.
What is needed is an automated laboratory management system which reduces the likelihood that the system loops endlessly when tracking the traceability of calibration standards calibrated by other calibration standards.
What is needed is a system which reduces the need for the maintenance of separate databases for test instruments and calibration standards.
Another area of interest in the calibration laboratory field is the use of statistics to analyze and characterize a population of measurement data. A population of measurement data is a group of like measurements, for example, a collection of measured values for a large number of resistance calibrations. The statistical analysis of a population of data depends on the size and distribution of the population. The collection of a population of data is difficult in known laboratory management systems as the form of the measurement data as stored in these systems is not necessarily standardized. Without this standardization, it is difficult to ascertain which measurement data stored in a system are alike.
One area of important statistical analysis is predictive maintenance scheduling. Predictive maintenance refers to analysis based on the period of calibration and the data collected at calibration service. The object of this scheduling is to predict a next calibration date for a test instrument at which the test instrument will still be in calibration and which also provides the longest period of service for the test instrument. A long service period for a test instrument is important as calibration service involves both the cost for the calibration service and the time that the test instrument is not available for productive work. Thus, a goal of predictive maintenance scheduling is to extend the dates between calibration servicing of a test instrument as much as possible. However, this goal must be balanced against the need for the test instrument to remain within calibration during the entire service period. Otherwise, an issue arises as to whether the equipment or goods verified by the test instrument are accurate. For example, if a standard is determined to be out of calibration at a calibration service for the standard, then each test instrument that was calibrated with the standard since the last calibration service for the standard was possibly inaccurately calibrated. As a result, the calibration laboratory must analyze the impact of the out of tolerance condition and possibly issue a recall to re-calibrate each test instrument calibrated with the standard. This, in turn, may require the customers owning the recalled equipment to issue recalls or perform field service to re-verify equipment verified with the recalled equipment.
Predictive scheduling analysis requires a significant body of measurement data regarding the period of time between calibration dates for equipment and the measurement data values obtained at the calibration dates. While it appears that such information would be available from previously known automated laboratory data management systems, the retrieval of measurement data from such systems is problematic. One difficulty in obtaining data from previously known automated laboratory management systems is the inconsistency of equipment identification in the work order records noted above. Thus, an attempt to retrieve all information related to a particular type of equipment may result in the inaccurate collection of data because some of the work order records may be improperly omitted. Such omissions may arise from typographical errors in the equipment identification in the work order record which causes the record to appear as not corresponding to the type of equipment to be analyzed.
What is needed is a system which facilitates the collection of technical data for all pieces of equipment which correspond to a particular type.
What is needed is a system which reduces the likelihood that technical data for a relevant test instrument will be omitted from a population of data required for some statistical data analysis.
In an effort to facilitate the tasks of a laboratory technician in collecting and analyzing data to calibrate equipment, automated calibration procedures (ACPs) have been developed. ACPs are computer programs, either available from third party vendors or custom development sources, which either perform a calibration procedure and collect measurement data or step a technician through a calibration procedure and prompt the technician for data generated during the performance of the procedure. The data collected by an ACP is stored in files on the computer executing the ACP. While the ACP facilitates a technician's tasks, it produces a file of calibration data which is not part of known automated laboratory management systems. However, known automated laboratory management systems require the technical data collected by an ACP to perform a variety of tasks. For example, known automated laboratory management systems generate certificates of calibration which require customer identification and technical data from the calibration service. To address the need of known automated laboratory management systems for technical data from an ACP, methods for transferring data files from ACPs to known automated laboratory management systems have been developed. Typically, the file transport programs which implement these methods require the conversion of the data from the format in which it is stored on the ACP computer to a compatible format for an automated laboratory management system. Additionally, transfers using these methods are performed after all of the data has been collected for a calibration procedure by an ACP and stored in a file by the ACP.
The known methods for transferring data files from an ACP to known automated laboratory management systems have a number of limitations. For one, any time a laboratory considers acquiring a new ACP, it must verify that the format of the data generated by the ACP can be converted by the file transport program used for the laboratory management system. As a result, a laboratory may be limited in the ACP programs it may consider. The alternative of developing or buying another file transport program to support an ACP is both expensive and time consuming. For another, file transport programs are used to transport files generated by an ACP after one or more calibration procedures are performed. The process of stopping between procedures to activate a file transport program, monitor the transfer, and then resume calibration servicing of equipment is time intensive and denigrates the productivity of the technician. Consequently, a laboratory may address this issue by using a file transport to transfer many files from one or more ACPs at a time in a batch mode operation. However, this extends the time required for the transfer operation. Additionally, the time that the technical data remains on the ACP, it is separated from the laboratory management system and may be corrupted before a file transfer can occur.
What is needed is a laboratory management system that accepts technical data from an ACP without requiring a file transport program. What is needed is a laboratory management system that can collect technical data from an ACP while a calibration procedure is being performed.